Webbing retractor

ABSTRACT

To simplify the structure of a webbing retractor, at a second locking mechanism 44 of the webbing retractor, when a gas generator is not operated, a cam engages with an outer peripheral groove of a lock ring, and a limit load by a torsion shaft is made to be a high load. On the other hand, when the gas generator is operated, the cam is moved apart from the outer peripheral groove of the lock ring, and the limit load by the torsion shaft is made to be a low load. Because only the cam is interposed between the lock ring and a piston which is driven by the gas generator, the number of parts of the second locking mechanism can be reduced, and the structure of the second locking mechanism can be made simple.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2007-050144, the disclosure of which is incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to a webbing retractor in which a force limiter mechanism limits, to a limit load, the load which is applied from a webbing to a vehicle occupant at the time of an emergency situation with respect to the vehicle.

2. Related Art

Among webbing retractors, there are those in which a torsion shaft limits, to a limit load, the load which is applied to a vehicle occupant from a webbing belt, and the limit load by the torsion shaft is alternated between a high load and a low load due to switching between a state in which a lock pawl meshes with a ratchet wheel and a state in which the lock pawl does not mesh with the ratchet wheel (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2005-1648).

However, in this webbing retractor, the meshing state and the non-meshing state of the lock pawl with the ratchet wheel is alternated between by the lock pawl being rotated due to a piston being driven and a cam plate being rotated. This is therefore a structure in which the cam plate and the lock pawl are interposed between the piston and the ratchet wheel, and there is a large number of parts and a complex structure.

Further, plural ratchet teeth are formed at the lock pawl, and the lock pawl meshes with the ratchet wheel at plural places. Therefore, there is the possibility that the aligning of the lock pawl with respect to the ratchet wheel will become complicated.

Moreover, as compared with the position where the lock pawl meshes with the ratchet wheel, the supporting position of the lock pawl (the position of a guide pin) is disposed at the side opposite to the direction of rotation in the pull-out direction of the ratchet wheel. Therefore, in order for the lock pawl to mesh with the ratchet wheel and prevent rotation of the ratchet wheel in the pull-out direction, the ratchet teeth of the lock pawl must be formed in shapes which are inclined toward the side opposite to the direction of rotation in the pull-out direction of the ratchet wheel. Due thereto, there is the possibility that the shape of the ratchet tooth portion of the lock pawl will become complex.

In addition, at the time when the piston is driven and the meshing of the lock pawl with the ratchet wheel is released, it is preferable to be able to suppress the meshing of the lock pawl with the ratchet wheel.

SUMMARY

In view of the aforementioned, the present invention provides a webbing retractor whose structure can be simplified, a webbing retractor in which the alignment of an operating member with respect to a moving member can be made to be simple, a webbing retractor in which the shape of the operating member can be made to be simple, and a webbing retractor in which it is possible to suppress the operating member being set in a non-operating state at the time when the operating member is operated.

A webbing retractor of a first aspect has: a winding shaft on which a webbing, which can be applied to a vehicle occupant, is wound, the webbing being pulled out by the winding shaft being rotated in a pull-out direction; a force limiter mechanism which, at a time of an emergency situation with respect to a vehicle, permits rotation of the winding shaft in the pull-out direction and limits a load, which is applied to the vehicle occupant from the webbing, to a limit load; and a switching portion having a driving member which is configured to be driven at a time of an emergency situation with respect to the vehicle, an operating member directly operated by driving of the driving member, and a moving member which is engaged with the operating member and movement of which is permitted by operation of the operating member, the switching portion switching the limit load from a high load to a low load in response to the movement of the moving member being permitted.

A webbing retractor of a second aspect has: a winding shaft on which a webbing, which can be worn by a vehicle occupant, is wound, the webbing being pulled out by the winding shaft being rotated in a pull-out direction; a force limiter mechanism which, at a time of an emergency situation with respect to a vehicle, permits rotation of the winding shaft in the pull-out direction and limits a load, which is applied to the vehicle occupant from the webbing, to a limit load; and a switching portion having a driving member which is configured to be driven at a time of an emergency situation with respect to the vehicle, and a moving member which is engaged with the driving member and movement of which is permitted by driving of the driving member, the switching portion switching the limit load from a high load to a low load in response to the movement of the moving member being permitted.

A webbing retractor of a third aspect has: a winding shaft on which a webbing, which can be worn by a vehicle occupant, is wound, the webbing being pulled out by the winding shaft being rotated in a pull-out direction; a force limiter mechanism which, at a time of an emergency situation with respect to a vehicle, permits rotation of the winding shaft in the pull-out direction and limits a load, which is applied to the vehicle occupant from the webbing, to a limit load; and a switching portion having an operating member which is configured to be operated at a time of an emergency situation with respect to the vehicle, and a moving member which is engaged with the operating member at one position with prevention and permission of movement thereof being alternated between by operation of the operating member, the switching portion switching the limit load between a high load and a low load in response to alternation between the operation and non-operation of the operating member.

A webbing retractor of a fourth aspect has: a winding shaft on which a webbing, which can be worn by a vehicle occupant, is wound, the webbing being pulled out by the winding shaft being rotated in a pull-out direction; a force limiter mechanism which, at a time of an emergency situation with respect to a vehicle, permits rotation of the winding shaft in the pull-out direction and limits a load, which is applied to the vehicle occupant from the webbing, to a limit load; and a switching portion having an operating member which is configured to be operated at a time of an emergency situation with respect to the vehicle, and a moving member which is engaged with the operating member with prevention and permission of movement thereof being alternated between by operation of the operating member, a supporting position of the operating member being disposed at a moving direction side with respect to an engaging position of the operating member, and the switching portion switching the limit load between a high load and a low load in response to alternation between the operation and non-operation of the operating member.

A webbing retractor of a fifth aspect has: a winding shaft on which a webbing, which can be worn by a vehicle occupant, is wound, the webbing being pulled out by the winding shaft being rotated in a pull-out direction; a force limiter mechanism which, at a time of an emergency situation with respect to a vehicle, permits rotation of the winding shaft in the pull-out direction and limits a load, which is applied to the vehicle occupant from the webbing, to a limit load; and a switching portion having an operating member which is configured to be operated via pressure of a fluid at a time of an emergency situation with respect to the vehicle and with an operated state thereof being maintained via the pressure of the fluid, and a moving member, prevention and permission of movement thereof being alternated between by operation of the operating member, the switching portion switching the limit load between a high load and a low load in response to alternation between the operation and non-operation of the operating member.

A webbing retractor of a sixth aspect is characterized that, in any one of the webbing retractors of the first to the fifth aspects, the winding shaft is hollow along the central axis thereof, the force limiter mechanism is accommodated within the winding shaft, and a first locking portion and the switching portion, which serves as a second locking portion, are coaxially connected at either end side of the winding shaft.

A webbing retractor of a seventh aspect is characterized that, in any one of the webbing retractors of the first to the fifth aspects, the force limiter mechanism, serving as a first energy absorbing member, includes a first deforming portion which is connected between a portion which is joined to the winding shaft and the first locking portion and a second deforming portion which is connected between the portion which is joined to the winding shaft and the second locking portion (the switching portion), and is twistable by a rotational force in the pull-out direction of the winding shaft.

A webbing retractor of a eighth aspect is characterized that, in any one of the webbing retractors of the first to the fifth aspects, a stopper accommodating hole for accommodating a stopper wire serving as a second energy absorbing member is formed in the winding shaft, one end portion of the stopper wire is disposed within a wire guiding portion which is formed at least either one of a first locking portion side end portion of the winding shaft and a winding shaft side end portion of the first locking portion, and the other end of the stopper wire is disposed within an accommodating hole formed in the second locking portion.

In the webbing retractor of the first aspect, the webbing, which can be applied to a vehicle occupant, is wound on the winding shaft. The webbing is pulled-out due to the winding shaft being rotated in the pull-out direction.

At a time of an emergency situation with respect to the vehicle, the force limiter mechanism permits rotation of the winding shaft in the pull-out direction such that the load, which is applied to the vehicle occupant from the webbing, is limited to the limit load.

At the switching portion, the driving member can be driven at a time of an emergency situation with respect to the vehicle. Due to the driving of the driving member, the operating member is operated, and movement of the moving member is permitted. The limit load by the force limiter mechanism is thereby alternated from high load to low load. Here, the operating member is directly operated by the driving of the driving member, and the operating member is engaged with the moving member. Therefore, because there is a structure in which only the operating member is interposed between the driving member and the moving member, the number of parts can be reduced, and the structure can be made to be simple.

In the webbing retractor of the second aspect, the webbing, which can be applied to a vehicle occupant, is wound on the winding shaft. The webbing is pulled-out due to the winding shaft being rotated in the pull-out direction.

At a time of an emergency situation with respect to the vehicle, the force limiter mechanism permits rotation of the winding shaft in the pull-out direction such that the load, which is applied to the vehicle occupant from the webbing, is limited to the limit load.

At the switching portion, at a time of an emergency situation with respect to the vehicle, the driving member can be driven. Due to the driving of the driving member, movement of the moving member is permitted. The limit load by the force limiter mechanism is thereby switched from high load to low load.

Here, the driving member is engaged with the moving member. Therefore, because there is a structure in which nothing is interposed between the driving member and the moving member, the number of parts can be reduced, and the structure can be made to be simple.

In the webbing retractor of the third aspect, the webbing, which can be applied to a vehicle occupant, is wound on the winding shaft. The webbing is pulled-out due to the winding shaft being rotated in the pull-out direction.

At a time of an emergency situation with respect to the vehicle, the force limiter mechanism permits rotation of the winding shaft in the pull-out direction such that the load, which is applied to the vehicle occupant from the webbing, is limited to the limit load.

At the switching portion, the operating member can be operated at a time of an emergency situation with respect to the vehicle. Due to the operation of the operating member, prevention and permission of movement of the moving member are alternated. The limit load by the force limiter mechanism is thereby alternated between high load and low load.

Here, the operating member can engage with the moving member at one position. Therefore, aligning of the operating member with respect to the moving member can be made to be easy.

In the webbing retractor of the fourth aspect, the webbing, which can be applied to a vehicle occupant, is wound on the winding shaft. The webbing is pulled-out due to the winding shaft being rotated in the pull-out direction.

At a time of an emergency situation with respect to the vehicle, the force limiter mechanism permits rotation of the winding shaft in the pull-out direction such that the load, which is applied to the vehicle occupant from the webbing, is limited to the limit load.

At the switching portion, the operating member can be operated at a time of an emergency situation with respect to the vehicle. Due to the operation of the operating member, prevention and permission of movement of the moving member are alternated. The limit load by the force limiter mechanism is thereby alternated between high load and low load.

Here, the operating member can engage with the moving member. The position at which the operating member is supported is disposed at the moving member moving direction side with respect to the engaging position of the operating member with the moving member. Therefore, in order for the operating member to engage with the moving member and prevent movement of the moving member, there is no need to make the engaging portion of the operating member with the moving member be a shape which is inclined toward the side opposite to the moving direction of the moving member. The shape of the engaging portion of the operating member with the moving member can be made to be simple.

In the webbing retractor of the fifth aspect, the webbing, which can be applied to a vehicle occupant, is wound on the winding shaft. The webbing is pulled-out due to the winding shaft being rotated in the pull-out direction.

At a time of an emergency situation with respect to the vehicle, the force limiter mechanism permits rotation of the winding shaft in the pull-out direction such that the load, which is applied to the vehicle occupant from the webbing, is limited to the limit load.

At the switching portion, the operating member can be operated at a time of an emergency situation with respect to the vehicle. Due to the operation of the operating member, prevention and permission of movement of the moving member are alternated. The limit load by the force limiter mechanism is thereby alternated between high load and low load.

Here, the operating member can be operated via pressure of a fluid. When the operating member is operated, the operating state thereof is maintained via the pressure of the fluid. Therefore, the operating member entering into a non-operating state can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:

FIG. 1 is an exploded perspective view showing the structure of a second locking mechanism of a webbing retractor relating to a first exemplary embodiment of the present invention;

FIG. 2 is a front view showing a summary of the structure of the second locking mechanism in the webbing retractor relating to the first exemplary embodiment of the present invention;

FIG. 3 is a front view corresponding to FIG. 2 and showing an operating state of the second locking mechanism in the webbing retractor relating to the first exemplary embodiment of the present invention;

FIG. 4 is a front view corresponding to FIG. 2 and showing an unlocked state of a lock ring of the second locking mechanism in the webbing retractor relating to the first exemplary embodiment of the present invention;

FIG. 5 is a front sectional view showing a summary of the structure of the webbing retractor relating to the first exemplary embodiment of the present invention;

FIG. 6 is an exploded perspective view showing the structure of the second locking mechanism of the webbing retractor relating to the first exemplary embodiment of the present invention;

FIG. 7A is a front view showing the positional relationship between a spool and a stopper wire in the webbing retractor relating to the first exemplary embodiment of the present invention, and showing a state before the stopper wire moves;

FIG. 7B is a front view showing the positional relationship between the spool and the stopper wire in the webbing retractor relating to the first exemplary embodiment of the present invention, and showing a state in which the stopper wire has moved;

FIG. 8 is a front view of a first lock base in the webbing retractor relating to the first exemplary embodiment of the present invention;

FIG. 9 is an exploded perspective view showing the structure of a second locking mechanism of a webbing retractor relating to a second exemplary embodiment of the present invention;

FIG. 10 is a front view showing a summary of the structure of the second locking mechanism in the webbing retractor relating to the second exemplary embodiment of the present invention;

FIG. 11 is a front view corresponding to FIG. 10 and showing an operating state of the second locking mechanism in the webbing retractor relating to the second exemplary embodiment of the present invention;

FIG. 12 is a front view corresponding to FIG. 10 and showing an unlocked state of a lock ring of the second locking mechanism in the webbing retractor relating to the second exemplary embodiment of the present invention;

FIG. 13 is an exploded perspective view showing the structure of a second locking mechanism of a webbing retractor relating to a third exemplary embodiment of the present invention;

FIG. 14 is a front view showing a summary of the structure of the second locking mechanism in the webbing retractor relating to the third exemplary embodiment of the present invention;

FIG. 15 is a front view corresponding to FIG. 14 and showing an operating state of the second locking mechanism in the webbing retractor relating to the third exemplary embodiment of the present invention;

FIG. 16 is a front view corresponding to FIG. 14 and showing an unlocked state of a lock ring of the second locking mechanism in the webbing retractor relating to the third exemplary embodiment of the present invention;

FIG. 17 is an exploded perspective view showing the structure of a second locking mechanism of a webbing retractor relating to a fourth exemplary embodiment of the present invention;

FIG. 18 is a front view showing a summary of the structure of the second locking mechanism in the webbing retractor relating to the fourth exemplary embodiment of the present invention;

FIG. 19 is a front view corresponding to FIG. 18 and showing an operating state of the second locking mechanism in the webbing retractor relating to the fourth exemplary embodiment of the present invention;

FIG. 20 is a front view corresponding to FIG. 18 and showing an unlocked state of a lock ring of the second locking mechanism in the webbing retractor relating to the fourth exemplary embodiment of the present invention;

FIG. 21 is an exploded perspective view showing the structure of a second locking mechanism of a webbing retractor relating to a fifth exemplary embodiment of the present invention;

FIG. 22 is a front view showing a summary of the structure of the second locking mechanism in the webbing retractor relating to the fifth exemplary embodiment of the present invention;

FIG. 23 is a front view corresponding to FIG. 22 and showing an operating state of the second locking mechanism in the webbing retractor relating to the fifth exemplary embodiment of the present invention;

FIG. 24 is a front view corresponding to FIG. 22 and showing an unlocked state of a lock ring of the second locking mechanism in the webbing retractor relating to the fifth exemplary embodiment of the present invention;

FIG. 25 is an exploded perspective view showing the structure of a second locking mechanism of a webbing retractor relating to a sixth exemplary embodiment of the present invention;

FIG. 26 is a front view showing a summary of the structure of the second locking mechanism in the webbing retractor relating to the sixth exemplary embodiment of the present invention;

FIG. 27 is a front view corresponding to FIG. 26 and showing an operating state of the second locking mechanism in the webbing retractor relating to the sixth exemplary embodiment of the present invention; and

FIG. 28 is a front view corresponding to FIG. 26 and showing an unlocked state of a lock ring of the second locking mechanism in the webbing retractor relating to the sixth exemplary embodiment of the present invention.

DETAILED DESCRIPTION First Exemplary Embodiment

A first exemplary embodiment of the present invention will be described next by using FIG. 1 through FIG. 8.

A summary of the structure of a webbing retractor 10 relating to the first exemplary embodiment of the present invention is shown in a cross-sectional view in FIG. 5.

As shown in FIG. 5, the webbing retractor 10 has a frame 12. The frame 12 has a plate-shaped rear plate 14 which is fixed to a vehicle body. A leg plate 16 extends, substantially orthogonally to the rear plate 14, from one transverse direction end portion of the rear plate 14. In contrast, a leg plate 18 extends, in the same direction as the direction in which the leg plate 16 extends, from the other transverse direction end portion of the rear plate 14. The frame 12 has a substantially convex shape as seen in plan view.

A spool 20 serving as a winding shaft is provided between the leg plate 16 and the leg plate 18. The axial direction of the spool 20 runs along the direction in which the leg plate 16 and the leg plate 18 oppose one another. The base end portion of a webbing belt 22 (seat belt), which is shaped as an elongated strip and serves as a webbing, is anchored to the axial direction intermediate portion of the spool 20. Due to the spool 20 rotating in a winding direction (the direction of arrow A in FIG. 2) which is one direction around the axis thereof, the spool 20 winds the webbing belt 22 from the base end side thereof and accommodates the webbing belt 22. The webbing belt 22 is pulled-out due to the spool 20 being rotated in a pull-out direction (the direction of arrow B in FIG. 2) which is the other direction around the axis thereof.

On the other hand, the spool 20 is hollow along its central axis. A torsion shaft 24, which serves as a force limiter mechanism and a first energy absorbing member, is accommodated within the spool 20. The torsion shaft 24 has a portion 26 which is joined to the spool. The portion 26 which is joined to the spool is positioned between the axial direction both ends of the spool 20. The torsion shaft 24 is integrally connected to the spool 20 at this portion 26 which is joined to the spool.

A rod-shaped first deforming portion 28 is formed continuously from the leg plate 16 side end surface of the portion 26 which is joined to the spool. A first joining portion 30 is formed at the leading end side of the first deforming portion 28, so as to be coaxial and integral with the first deforming portion 28. The first joining portion 30 is coaxially and integrally connected to a first lock base 34 which serves as a rotating body which structures a first locking mechanism 32 serving as a first locking portion.

The first lock base 34 is fit-together by insertion from the leg plate 16 side end portion of the spool 20, so as to be coaxial with the spool 20 and able to rotate relative to the spool 20. However, due to the first joining portion 30 being connected integrally to the first lock base 34 as described above, the first lock base 34 is basically connected coaxially and integrally with the spool 20.

A first lock pawl 36 is provided at the radial direction outer side of the first lock base 34. The first lock pawl 36 is pivotally-supported so as to rotate freely at the leg plate 16. When the first lock pawl 36 rotates in a predetermined one direction, ratchet teeth formed at the first lock pawl 36 approach the outer peripheral portion of the first lock base 34, and can mesh-together with the ratchet teeth which are formed at the outer peripheral portion of the first lock base 34.

On the other hand, at the side of the first lock base 34 opposite to the side where the spool 20 is disposed, a rotating member 38 is provided so as to be coaxial with the first lock base 34 and able to rotate relative to the first lock base 34. The rotating member 38 is structured so as to rotate following the first lock base 34, due to the biasing force of an unillustrated biasing portion such as a compression coil spring, a torsion coil spring, or the like.

Further, although details thereof are not illustrated, the first locking mechanism 32 has one or plural restricting portions which restrict rotation of the rotating member 38. When a large inertia arises at the vehicle at the time of a rapid deceleration of the vehicle (at the time of an emergency), or when the first lock base 34 rotates rapidly in the pull-out direction, the restricting portion operates, and rotation of the rotating member 38 is restricted. The first lock pawl 36 moves so as to approach the outer peripheral portion of the first lock base 34, interlockingly with the relative rotation between the first lock base 34 and the rotating member 38 which arises at the time when the first lock base 34 attempts to rotate in the pull-out direction in the state in which rotation of the rotating member 38 is restricted.

On the other hand, a rod-shaped second deforming portion 40 is formed continuously from the leg plate 18 side end surface of the portion 26 which is joined to the spool. A second joining portion 42 is formed coaxially and integrally with the second deforming portion 40, at the leading end side of the second deforming portion 40. The second joining portion 42 is connected coaxially and integrally to a second lock base 46 which structures a second locking mechanism 44 serving as a switching portion (second locking portion).

The second lock base 46 is fit-together by insertion from the leg plate 18 side end portion of the spool 20, so as to be coaxial with the spool 20 and able to rotate relative to the spool 20. However, due to the second joining portion 42 being connected integrally to the second lock base 46 as described above, the second lock base 46 is basically connected coaxially and integrally with the spool 20.

As shown in FIG. 1 and FIG. 2, a pair of pawl accommodating portions 48 are formed at the second lock base 46. The pawl accommodating portions 48 are open at portions of the outer periphery of the second lock base 46. The pawl accommodating portions 48 open at the end surface of the second lock base 46 which end surface is at the opposite side of the spool 20. Second lock pawls 50 are accommodated in the pawl accommodating portions 48. Each of the second lock pawls 50 is pivotally-supported so as to be rotatable around an axis parallel to the axis of the spool 20, by a pawl supporting pin 52 formed within the pawl accommodating portion 48. The second lock pawls 50 are basically accommodated in the pawl accommodating portions 48, respectively. When the second lock pawl 50 rotates in one direction around the pawl supporting pin 52, the distal end side of the second lock pawl 50 projects-out to the outer side from the open portion at the outer peripheral portion of the pawl accommodating portion 48.

On the other hand, a rotating disc 54 is provided at the side of the second lock base 46 opposite to the side where the spool 20 is located. The rotating disc 54 basically is pivotally-supported at the spool 20 so as to be coaxial with the spool 20 and able to rotate relative to the spool 20. A pair of guiding pins 56 are formed to project-out from the second lock base 46 side end surface of the rotating disc 54. The guiding pins 56 are provided so as to correspond to the aforementioned second lock pawls 50.

Long holes 58 are formed in the second lock pawls 50 respectively, in correspondence with the guiding pins 56. The guiding pins 56 are disposed in the long holes 58. The widthwise dimensions of the long holes 58 are slightly larger than the outer diameters of the guiding pins 56. When the guiding pins 56 rotate together with the rotating disc 54 in one direction around the spool 20, the guiding pins 56 push the inner walls of the long holes 58 and rotate the second lock pawls 50 around the pawl supporting pins 52.

A flat-plate-shaped plate 60 is formed to project from the second lock base 46 side end surface of the rotating disc 54. A spring accommodating hole 62 which is rectangular is formed in the second lock base 46 in correspondence with the plate 60. A rotating disc biasing spring 64 is accommodated within the spring accommodating hole 62.

The rotating disc biasing spring 64 is a compression coil spring. One end of the rotating disc biasing spring 64 press-contacts the inner wall of the spring accommodating hole 62. The other end of the rotating disc biasing spring 64 press-contacts the plate 60 which is disposed in the spring accommodating hole 62. The rotating disc 54 can rotate in one direction around the spool 20, due to the plate 60 receiving the biasing force of the rotating disc biasing spring 64. When the rotating disc 54 rotates in this direction, the guiding pins 56 rotate the second lock pawls 50 in the direction around the pawl supporting pins 52.

On the other hand, as shown in FIG. 5 and FIG. 6, a through-hole 66 is formed in the floor portion of the spring accommodating hole 62. A stopper accommodating hole 70 is formed in the spool 20 in correspondence with the through-hole 66. The stopper accommodating hole 70 is parallel to the axial center of the spool 20. One end of the stopper accommodating hole 70 opens at the end portion of the spool 20 at the first lock base 34 side. The other end of the stopper accommodating hole 70 opens at the end portion of the spool 20 at the second lock base 46 side. The inner radial dimension of the stopper accommodating hole 70 does not change from the one end to the other end thereof.

A stopper wire 74, which serves as a second energy absorbing member and a controlling portion, is accommodated within the stopper accommodating hole 70. The stopper wire 74 is formed in the shape of a rod which is long along the axial direction of the spool 20. One end side of the stopper wire 74 projects-out to the exterior of the stopper accommodating hole 70 from the open end at the first lock base 34 side of the stopper accommodating hole 70.

A wire guiding groove 82 (see FIG. 7A) is formed in correspondence with the portion of the stopper wire 74 which projects-out from the spool 20, at least either one of the first lock base 34 side end portion of the spool 20 and the spool 20 side end portion of the first lock base 34 (in the present exemplary embodiment, the wire guiding groove 82 is formed at the end portion of the spool 20). The wire guiding groove 82 is curved such that the center of curvature thereof is the central axis of the spool 20. One end side of the stopper wire 74 is disposed within the wire guiding groove 82, and is curved so as to follow the wire guiding groove 82.

Further, the one end portion of the stopper wire 74 is bent toward the first lock base 34 within the wire guiding groove 82. The one end portion of the stopper wire 74 is disposed in a wire anchoring hole 84 which is formed in the first lock base 34 shown in FIG. 8 as well.

On the other hand, the other end side of the stopper wire 74 projects-out to the exterior of the spool 20 from the second lock base 46 side end portion of the stopper accommodating hole 70. The stopper wire 74 passes through the through-hole 66, and is disposed within the spring accommodating hole 62 at the side of the plate 60 opposite to the side at which the rotating disc biasing spring 64 is disposed. This other end of the stopper wire 74 interferes with the plate 60 which attempts to rotate due to the biasing force of the rotating disc biasing spring 64.

As shown in FIG. 1 and FIG. 2, a base 86 is connected integrally to the leg plate 18 at the outer side of the leg plate 18. A circular hole 88 is formed in the base 86, coaxially with the spool 20. The inner diameter of the circular hole 88 is sufficiently larger than the second lock base 46, and the second lock base 46 is passed-through the circular hole 88. A lock ring 90, which serves as a moving member, is pivotally-supported at the circular hole 88 so as to rotate freely. The lock ring 90 is formed in a ring shape on the whole. Further, inner ratchets 92 are formed at the inner peripheral portion of the lock ring 90. When the second lock pawls 50 rotate in one direction around the pawl supporting pins 52 and the leading end sides of the second lock pawls 50 project-out to the outer sides of the pawl accommodating portions 48, second pawl ratchets 94 at the leading end sides of the second lock pawls 50 mesh-together with the inner ratchets 92.

An outer peripheral groove 96, which is triangular in cross-portion and serves as an engaged portion, is formed at a portion of the outer periphery of the lock ring 90. A cam accommodating hole 98, which communicates with the circular hole 88, is formed in the base 86 in correspondence with the outer peripheral groove 96. A cam 100, which is shaped as a substantially rectangular plate and serves as an operating member, is provided at the inner side of the cam accommodating hole 98. The cam 100 is supported so as to rotate freely at a supporting shaft 102 which is formed to project-out from the leg plate 18. The supporting shaft 102 is disposed at the pull-out direction side with respect to the outer peripheral groove 96 of the lock ring 90. A corner portion 100A, which is at one end side of the cam 100 and serves as an engaging portion, can engage with a winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90. Due to the dead weight of the cam 100, rotational force, in the direction in which the corner portion 100A separates from the outer peripheral groove 96 of the lock ring 90, is applied to the cam 100. A shear pin 104, which serves as a positioning portion and is formed to project-out from the leg plate 18, passes through the cam 100. Rotation of the cam 100 is thereby restricted, and the corner portion 100A of the cam 100 engages with (abuts) the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90.

In the state in which the corner portion 100A of the cam 100 is engaged with the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90, when the lock ring 90 attempts to rotate in the pull-out direction, the corner portion 100A of the cam 100 is pushed in the pull-out direction by the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90, and rotational force, in the direction in which the corner portion 100A separates from the outer peripheral groove 96 of the lock ring 90, acts on the cam 100. However, due to the rotation of the cam 100 being restricted by the shear pin 104, the shear pin 104 receives the rotational force of the lock ring 90 in the pull-out direction, and rotation of the lock ring 90 in the pull-out direction is restricted (prevented).

A cylinder accommodating hole 106 is formed in the base 86, beneath the cam 100. The cylinder accommodating hole 106 communicates with the aforementioned cam accommodating hole 98. A tubular cylinder 108 is fixed to the inner side of the cylinder accommodating hole 106. A piston 110 serving as a driving member is accommodated in the upper end portion of the cylinder 108. The upper end of the piston 110 projects-out into the cam accommodating hole 98.

A gas generator 112 (micro gas generator) serving as a driving portion is fixed to the lower end portion of the cylinder 108. The gas generator 112 is disposed at the inner side of a generator accommodating hole 114 formed in the base 86, and is fixed to the base 86. Chemical agents, such as an igniting agent and a gas generating agent and the like, and an igniting device, which ignites the igniting agent due to an electric ignition signal being inputted thereto, are accommodated in the gas generator 112. The igniting device of the gas generator 112 is connected to an unillustrated ECU (control device).

The ECU is connected directly or indirectly to both a danger predicting portion and a physique detecting portion. The danger predicting portion directly or indirectly detects that the vehicle has entered a state of rapid deceleration or that the vehicle will likely enter into a state of rapid deceleration. Other than an acceleration sensor which senses a state of rapid deceleration of the vehicle, the danger predicting portion may be, for example, a distance measuring sensor which detects that the distance to an obstacle in front of the vehicle has become less than a given value, or the like. The physique detecting portion directly or indirectly detects the physique of the vehicle occupant who is seated in the seat, and is, for example, a load sensor which detects the load applied to the seat of the vehicle, a belt sensor which detects that the webbing belt 22 has been pulled-out by greater than or equal to a given amount from the spool 20, or the like.

When the ECU judges, on the basis of the signal from the danger predicting portion, that the vehicle has entered into a state of rapid deceleration or that the vehicle will likely enter into a state of rapid deceleration, and judges that the physique of the vehicle occupant seated in the seat is less than a reference value which is determined in advance, the ignition signal is output from the ECU to the igniting device of the gas generator 112, and the gas generator 112 is operated.

When the igniting agent is ignited due to the ignition signal being input to the igniting device of the gas generator 112, and further, the igniting agent which is ignited burns the gas generating agent, gas (a fluid) is generated instantaneously within the gas generator 112. The pressure of this gas works to push-out (drive) the piston 110 upward via the cylinder 108. Due to the piston 110, which is pushed-out toward the upper side of the cylinder 108, pushing the other end side portion of the cam 100 upward, the cam 100 rotates (operates) in the direction of moving the corner portion 100A away from the outer peripheral groove 96 of the lock cylinder 90, while the cam 100 breaks the shear pin 104.

The side of the base 86 at the side opposite to the leg plate 18 is covered by a cover (not shown) which is made of resin and serves as a covering member. The second locking mechanism 44 is accommodated at the interior of the cover.

Operation and effects of the present exemplary embodiment will be described next.

(Operation of First Locking Mechanism 32)

At the webbing retractor 10, in a state in which the webbing belt 22 which is pulled-out from the spool 20 is applied to the body of a vehicle occupant, when, for example, the vehicle enters into a state of rapid deceleration and the first locking mechanism 32 operates, first, rotation of the rotating member 38 in the pull-out direction is restricted.

Then, when the body of the vehicle occupant, which attempts to move forward due to the inertia at the time of the rapid deceleration of the vehicle, suddenly pulls the webbing belt 22 and attempts to rotate the spool 20 in the pull-out direction, the first lock base 34, which is integrally connected to the spool 20 via the torsion shaft 24, rotates in the pull-out direction.

Here, in this state, if rotation of the rotating member 38 in the pull-out direction is restricted as described above, relative rotation arises between the first lock base 34 and the rotating member 38, and the first lock pawl 36 approaches the first lock base 34.

In this way, the ratchet teeth of the first lock pawl 36 mesh-together with the ratchet teeth of the first lock base 34. Rotation of the first lock base 34 in the pull-out direction, and eventually, rotation of the spool 20 in the pull-out direction, is restricted, and pulling-out of the webbing belt 22 from the spool 20 is restricted. In this way, the body of the vehicle occupant, which attempts to move forward, can be reliably restrained by the webbing belt 22.

(Operation of Torsion Shaft 24)

In the state in which the rotation of the first lock base 34 is restricted by the first lock pawl 36 as described above, if the body of the vehicle occupant pulls the webbing belt 22 by an even greater force and the rotational force of the spool 20 in the pull-out direction, which is based on this pulling force, exceeds the mechanical strength of the first deforming portion 28, the first deforming portion 28 twists while the first joining portion 30 remains connected to the first lock base 34, and the spool 20 rotates in the pull-out direction by the amount of this twisting.

Accordingly, the webbing belt 22 is pulled-out from the spool 20 by the amount of rotation of the spool 20 in the pull-out direction. In this way, the force by which the webbing belt 22 restrains the vehicle occupant weakens slightly, and the energy provided for pulling the webbing belt 22 is absorbed by the amount of the aforementioned twisting deformation.

(Operation of Stopper Wire 74)

As described above, the rotation of the spool 20 in the pull-out direction with respect to the first lock base 34 is the rotation of the first lock base 34 in the winding direction relative to the spool 20. When the first lock base 34 rotates relative to the spool 20 in the winding direction in this way, the stopper wire 74 is pulled while being guided by the wire guiding groove 82 of the first lock base 34, in a state in which one end of the stopper wire 74 remains disposed in the wire anchoring hole 84 formed in the first lock base 34.

However, the longitudinal direction of the stopper wire 74 runs along the axial direction of the spool 20 at the inner side of the stopper accommodating hole 70, whereas the direction in which the first lock base 34 pulls the stopper wire 74 is the winding direction. Therefore, as shown in FIG. 7B, the stopper wire 74 which is pulled by the first lock base 34 follows the wire guiding groove 82, while being strongly rubbed at the edge of the first lock base 34 side open end of the stopper accommodating hole 70, and the stopper wire 74 is deformed such that the longitudinal direction thereof becomes the longitudinal direction of the wire guiding groove 82, i.e., the peripheral direction of rotation of the spool 20.

Due also to the stopper wire 74 being pulled and deformed in this way, the force by which the webbing belt 22 restrains the vehicle occupant weakens slightly, and the energy provided for pulling the webbing belt 22 is absorbed by the amount of deformation of the stopper wire 74. The energy absorption amount corresponding to the amount of deformation of the stopper wire 74 is superposed on the energy absorption amount corresponding to the amount of twisting of the first deforming portion 28, and the energy provided for pulling the webbing belt 22 can be absorbed effectively.

(Operation of Second Locking Mechanism 44)

When the stopper wire 74 moves at the inner side of the stopper accommodating hole 70 toward the first lock base 34 side as described above, the other end side of the stopper wire 74 which is disposed in the spring accommodating hole 62 passes-through the through-hole 66 and comes out from the spring accommodating hole 62, and is pulled into the stopper accommodating hole 70 from the lock base 46 side end portion of the stopper accommodating hole 70. When the stopper wire 74 is pulled-out from the spring accommodating hole 62 in this way, the interference of the stopper wire 74 with respect to the plate 60 is released. The plate 60, at which interference from the stopper wire 74 is released, receives the biasing force of the rotating disc biasing spring 64 and rotates within the spring accommodating hole 62.

Because the plate 60 is integral with the rotating disc 54, due to the plate 60 rotating by the biasing force of the rotating disc biasing spring 64, the rotating disc 54 rotates in the winding direction with respect to the second lock base 46. When the rotating disc 54 rotates in the winding direction with respect to the second lock base 46, the guiding pins 56 push the inner walls of the long holes 58, and cause the second lock pawls 50 to rotate in one direction around the pawl supporting pins 52.

When the second lock pawls 50 rotate in this way, the leading ends of the second lock pawls 50 project-out to the exterior of the second lock base 46, and the second lock pawl ratchets 94 of the leading ends of the second lock pawls 50 mesh-together with the inner ratchet 92 of the lock ring 90 (see FIG. 3).

The spool 20, at which the webbing belt 22 is being pulled, attempts to rotate in the pull-out direction. Therefore, the second lock pawls 50 attempt to rotate in the pull-out direction together with the second lock base 46.

Accordingly, the rotating force of the second lock base 46 in the pull-out direction is transmitted to the lock ring 90 which the second pawls 50 are meshed with, and the lock ring 90 attempts to rotate in the pull-out direction. In this state, if the corner portion 100A of the cam 100 is engaged with the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90, rotation of the lock ring 90 in the pull-out direction is restricted by the cam 100.

When rotation of the lock ring 90 in the pull-out direction is restricted, rotation of the second lock base 46 in the pull-out direction also is restricted. In this state, when the rotational force in the pull-out direction of the spool 20, which is based on the pulling force at the time when the body of the vehicle occupant pulls the webbing belt 22, exceeds the sum of the mechanical strength of the first deforming portion 28 and the mechanical strength of the second deforming portion 40, the second deforming portion 40 as well as the first deforming portion 28 are twisted, in a state in which the second joining portion 42 remains connected to the second lock base 46. The spool 20 rotates in the pull-out direction by the amount of this twisting.

Accordingly, the webbing belt 22 is pulled-out from the spool 20 by the amount of rotation of the spool 20 in the pull-out direction. In this way, the force by which the webbing belt 22 restrains the vehicle occupant weakens slightly, and the energy provided for pulling the webbing belt 22 is absorbed by aforementioned amount of twisting deformation. Therefore, energy absorption by the twisting deformation of the first deforming portion 28 and the second deforming portion 40 arises, and the limit load by the torsion shaft 24 is made to be a high load.

On the other hand, as shown in FIG. 4, before the first locking mechanism 32 operates, when the vehicle enters a state of rapid deceleration or a state immediately before rapid deceleration, and the ECU judges, on the basis of the signal from the physique detecting portion, that the physique of the vehicle occupant seated in the seat is less than the predetermined reference value, and the ignition signal is thereby output from the ECU, the gas generator 112 operates. When the gas generator 112 operates, the piston 110 is pushed toward the upper side of the cylinder 108 and pushes the other end side portion of the cam 100 upward. The cam 100 thereby rotates while breaking the shear pin 104, and the corner portion 100A of the cam 100 is separated from the outer peripheral groove 96 of the lock ring 90.

In this state, when the rotating force of the spool 20 in the pull-out direction is transmitted to the lock ring 90 via the second lock base 46 and the second lock pawls 50, the lock ring 90 rotates in the pull-out direction together with the spool 20. Accordingly, in this state, twisting occurs at the first deforming portion 28, but twisting does not occur at the second deforming portion 40. Therefore, only energy absorption due to twisting deformation of the first deforming portion 28 arises, and the limit load by the torsion shaft 24 is made to be a low load.

Namely, in the present exemplary embodiment, by controlling the gas generator 112, it is possible to selectively switch to a mode (high load mode) which causes deformation at the second deforming portion 40, and a mode (low load mode) which does not cause deformation at the second deforming portion 40. In this way, appropriate energy absorption corresponding to the physique of the vehicle occupant to which the webbing belt 22 is applied, or the like, is possible.

When the gas generator 112 is not operated, the cam 100 is engaged with the outer peripheral groove 96 of the lock ring 90, and the limit load by the torsion shaft 24 is made to be a high load. On the other hand, when the gas generator 112 is operated, the cam 100 is moved apart from the outer peripheral groove 96 of the lock ring 90, and the limit load by the torsion shaft 24 is made to be a low load.

In this way, the cam 100 is, due to the operation of the gas generator 112, changed from a state of being engaged with the outer peripheral groove 96 of the lock ring 90 (the high load mode) to a state of being separated from the outer peripheral groove 96 of the lock ring 90 (the low load mode). Therefore, as compared with a case in which the cam 100 is changed by operation of the gas generator 112 from a state of being separated from the outer peripheral groove 96 of the lock ring 90 (the low load mode) to a state of being engaged with the outer peripheral groove 96 of the lock ring 90 (the high load mode), the structure can be simplified, and the limit load by the torsion shaft 24 can be made to be a high load at an early stage, and, even if operation of the gas generator 112 is late, the amount of movement of the vehicle occupant can be suppressed because the limit load by the torsion shaft 24 is maintained at a high load. Further, because the cam 100 is changed from the state of being engaged with the outer peripheral groove 96 of the lock ring 90 to the state of being separated from the outer peripheral groove 96 of the lock ring 90, the precision of assembling the cam 100 with respect to the outer peripheral groove 96 of the lock ring 90 is good, and there is no loss of driving force between the lock ring 90 and the cam 100. Therefore, excessive force is not needed at the cam 100, and the operation of the cam 100 can be made to be stable.

Here, the second locking mechanism 44 is structured such that only the cam 100 is interposed between the lock ring 90 and the piston 110 which is driven by the gas generator 112. Therefore, the number of parts of the second locking mechanism 44 can be reduced, and the structure of the second locking mechanism 44 can be made to be simple. In this way, the work of assembling the second locking mechanism 44 can be made to be easy, and costs can be reduced.

Further, the cam 100 is engaged with the outer peripheral groove 96 of the lock ring 90 at one position (the corner portion 100A). Therefore, the aligning of the cam 100 with respect to the outer peripheral groove 96 of the lock ring 90 can be made to be simple, the precision of assembling the cam 100 with respect to the outer peripheral groove 96 of the lock ring 90 can easily be improved, and the cam 100 can appropriately restrict rotation of the lock ring 90 in the pull-out direction.

As compared with the position where the cam 100 engages the lock ring 90 (the position of the corner portion 100A), the position where the cam 100 is supported (the position of the supporting shaft 102) is disposed at the lock ring 90 pull-out direction side. Therefore, in order for the corner portion 100A of the cam 100 to engage with the outer peripheral groove 96 of the lock ring 90 and prevent rotation of the lock ring 90 in the pull-out direction, there is no need to form an engaging portion of the cam 100 which engages with the outer peripheral groove 96 of the lock ring 90 (i.e., the corner portion 100A) in a shape which is inclined toward the winding direction of the lock ring 90. The shape of this engaging portion of the cam 100 can be made to be simple, and the strength of the engaging portion of the cam 100 can be made to be high. Further, because the load from the outer peripheral groove 96 of the lock ring 90 can be received at the supporting shaft 102 as well, the engagement of the cam 100 with the lock ring 90 can be stabilized.

Moreover, after the gas generator 112 is operated and the corner portion 100A of the cam 100 is moved apart from the outer peripheral groove 96 of the lock ring 90, even if the corner portion 100A of the cam 100 again engages with the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90, the corner portion 100A of the cam 100 is pushed by the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90, and is moved away from the outer peripheral groove 96 of the lock ring 90. Therefore, it is possible to prevent rotation of the lock ring 90 in the pull-out direction from being restricted unnecessarily after the gas generator 112 is operated.

Note that the present exemplary embodiment is a structure in which rotation of the cam 100 is restricted by the shear pin 104, but may be a structure in which rotation of the cam 100 is not restricted by the shear pin 104. In this case, when the lock ring 90 rotates in the pull-out direction and the corner portion 100A of the cam 100 is pushed by the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90, rotational force in the direction in which the corner portion 100A approaches the lock ring 90 acts on the cam 100. Moreover, it is preferable to utilize a structure in which rotational force in the direction of the corner portion 100A approaching the outer peripheral groove 96 of the lock ring 90 is applied due to the dead weight of the cam 100 itself, or a structure in which a positioning portion, which prevents rotation of the cam 100 at usual times of the vehicle and whose prevention of the rotation of the cam 100 is released at times of rapid deceleration of the vehicle, is provided at the cover or the like.

Further, the present exemplary embodiment may be structured such that the state, in which the corner portion 100A of the cam 100 is separated from the outer peripheral groove 96 of the lock ring 90, is maintained by maintaining the state in which the interior of the cylinder 108 is made to be high pressure due to the gas generated by the gas generator 112 and the piston 110 is pushed-out toward the upper side of the cylinder 108. In this way, after the gas generator 112 is operated, the corner portion 100A of the cam 100 can reliably be prevented from engaging with the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90, and it is possible to reliably prevent rotation of the lock ring 90 in the pull-out direction from being restricted unnecessarily.

Second Exemplary Embodiment

A second exemplary embodiment of the present invention will be described next by using FIG. 9 through FIG. 12.

A webbing retractor 200 relating to the present exemplary embodiment has a structure which is substantially similar to that of the first exemplary embodiment, but differs with respect to the following points.

As shown in FIG. 9 and FIG. 10, at the webbing retractor 200 relating to the present exemplary embodiment, a stopper placement hole 202, which is shaped as a rectangular plate and serves as an engaged portion, is formed at a portion of the outer periphery of the lock ring 90. The lower end of the stopper placement hole 202 is open from the outer periphery of the lock ring 90. A stopper accommodating hole 204, which communicates with the circular hole 88, is formed at the base 86 so as to correspond to the stopper placement hole 202. A stopper 206, which is shaped substantially as a rectangular plate and serves as an operating member, is accommodated at the inner side of the stopper placement hole 202. The stopper 206 is engaged with (placed at) the lock ring 90. The stopper 206 projects-out from the outer periphery of the lock ring 90 into the stopper accommodating hole 204, and abuts a pull-out direction side surface 204A of the stopper accommodating hole 204. A shear pin placement recess 208, which is rectangular in cross-portion, is formed at the upper portion of the stopper 206. A solid-cylindrical shear pin 210 is formed at the outer peripheral surface of the stopper placement hole 202. Due to the bottom surface of the shear pin placement recess 208 being abutted with the shear pin 210, the entire stopper 206 is prevented from being accommodated completely within the stopper placement hole 202. The stopper 206 is prevented from falling out from the stopper placement hole 202 by a shear pin (not shown) which serves as a positioning portion and is formed to project-out from the leg plate 18. Note that the stopper 206 may be prevented from falling out from the stopper placement hole 202 by, for example, being press-fit into the inner side of the stopper placement hole 202 as a positioning portion, or the like.

In the state in which the stopper 206 projects-out from the outer periphery of the lock ring 90 and is abutted with the pull-out direction side surface 204A of the stopper accommodating hole 204, when the lock ring 90 attempts to rotate in the pull-out direction, the pull-out direction side surface 204A of the stopper accommodating hole 204 receives the rotational force of the lock ring 90 in the pull-out direction via the stopper 206, such that rotation of the lock ring 90 in the pull-out direction is restricted (prevented).

The cylinder accommodating hole 106 of the base 86 communicates with the stopper accommodating hole 204. The upper end of the piston 110, which is accommodated at the upper end portion of the cylinder 108 which is fixed to the inner side of the cylinder accommodating hole 106, projects-out into the stopper accommodating hole 204 and is disposed below the stopper 206.

When the gas generator 112 is operated and the piston 110 is pushed-out toward the upper side of the cylinder 108, due to the piston 110 pushing the stopper 206 upward, the entire stopper 206 is completely accommodated (operated) within the stopper placement hole 202 while breaking the shear pin 210 and the shear pin which is formed to project-out from the leg plate 18.

As shown in FIG. 11, in the state in which the vehicle enters a state of rapid deceleration, and the second lock pawls 50 mesh-together with the lock ring 90, and the lock ring 90 attempts to rotate in the pull-out direction via the spool 20, the second lock base 46 and the second lock pawls 50, if the stopper 206 projects-out from the outer periphery of the lock ring 90 and is abutted with the pull-out direction side surface 204A of the stopper accommodating hole 204, rotation of the lock ring 90 in the pull-out direction is restricted by the stopper 206. Therefore, energy absorption due to twisting deformation of the first deforming portion 28 and the second deforming portion 40 arises, and the limit load by the torsion shaft 24 is made to be a high load.

On the other hand, as shown in FIG. 12, before the first locking mechanism 32 operates, when the vehicle enters into a state of rapid deceleration or a state immediately before rapid deceleration and the gas generator 112 is operated, due to the piston 110 being pushed-out toward the upper side of the cylinder 108 and the piston 110 pushing the stopper 206 upward, the entire stopper 206 is completely accommodated within the stopper placement hole 202 while breaking the shear pin 210 and the shear pin which is formed to project-out from the leg plate 18. In this state, if rotational force in the pull-out direction is transmitted to the lock ring 90 via the spool 20, the second lock base 46 and the second lock pawls 50, the lock ring 90 rotates in the pull-out direction. Therefore, only energy absorption due to twisting deformation of the first deforming portion 28 arises, and the limit load by the torsion shaft 24 is made to be a low load.

Here, the second locking mechanism 44 is structured such that only the stopper 206 is interposed between the lock ring 90 and the piston 110 which is driven by the gas generator 112. Therefore, the number of parts of the second locking mechanism 44 can be reduced, and the structure of the second locking mechanism 44 can be made to be simple. In this way, the work of assembling the second locking mechanism 44 can be made to be easy, and costs can be reduced.

Further, the stopper 206 is engaged with the stopper placement hole 202 of the lock ring 90 at one position (the upper portion). Therefore, the aligning of the stopper 206 with respect to the lock ring 90 can be made to be simple, the precision of assembling the stopper 206 with respect to the stopper placement hole 202 of the lock ring 90 can easily be improved, and the stopper 206 can appropriately restrict rotation of the lock ring 90 in the pull-out direction.

The stopper 206 is partially accommodated in the stopper placement hole 202 of the lock ring 90, and projects-out from the outer periphery of the lock ring 90 and is abutted with the pull-out direction side surface 204A of the stopper accommodating hole 204. Therefore, the shape of the stopper 206 for preventing rotation of the lock ring 90 in the pull-out direction can be made to be simple, and the strength of the stopper 206 can be made to be high.

Further, after the gas generator 112 is operated, the stopper 206 is prevented by the piston 110 from projecting-out from the outer periphery of the lock ring 90 by maintaining the state in which interior of the cylinder 108 is made to be high pressure due to the gas generated by the gas generator 112 and the piston 110 is pushed-out toward the upper side of the cylinder 108. Therefore, after the gas generator 112 is operated, the stopper 206 can reliably be prevented from abutting the pull-out direction side surface 204A of the stopper accommodating hole 204, and it is possible to reliably prevent rotation of the lock ring 90 in the pull-out direction from being restricted unnecessarily.

Third Exemplary Embodiment

A third exemplary embodiment of the present invention will be described next by using FIG. 13 through FIG. 16.

A webbing retractor 300 relating to the present exemplary embodiment has a structure which is substantially similar to that of the first exemplary embodiment, but differs with respect to the following points.

As shown in FIG. 13 and FIG. 14, in the webbing retractor 300 relating to the present exemplary embodiment, the winding direction side surface 96A of the outer peripheral groove 96 at the outer periphery of the lock ring 90 is disposed horizontally. A piston accommodating hole 302, which communicates with the circular hole 88, is formed in the base 86 so as to correspond to the outer peripheral groove 96.

The cylinder accommodating hole 106 of the base 86 communicates with the piston accommodating hole 302. The piston 110, which is partially accommodated at the upper end portion of the cylinder 108 which is fixed to the inner side of the cylinder accommodating hole 106, functions also as an operating member, and projects-out into the piston accommodating hole 302. The piston 110 is formed substantially in the shape of a sideways T-shaped plate, and the upper end of the piston 110 engages with (abuts) the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90. The piston 110 is positioned by a positioning portion (e.g., a positioning projection which is formed at the cover).

In the state in which the upper end of the piston 110 is engaged with the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90, if the lock ring 90 attempts to rotate in the pull-out direction, the piston 110 receives the rotational force of the lock ring 90 in the pull-out direction, and rotation of the lock ring 90 in the pull-out direction is restricted (prevented).

When the gas generator 112 is operated, the piston 110 is pushed-out toward the lateral side of the upper end portion of the cylinder 108 while breaking the positioning portion (i.e., is driven and operated), and the engagement of the upper end of the piston 110 with the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90 is released.

As shown in FIG. 15, in the state in which the vehicle enters a state of rapid deceleration, and the second lock pawls 50 mesh-together with the lock ring 90, and the lock ring 90 attempts to rotate in the pull-out direction via the spool 20, the second lock base 46 and the second lock pawls 50, if the upper end of the piston 110 is engaged with the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90, rotation of the lock ring 90 in the pull-out direction is restricted by the piston 110. Therefore, energy absorption due to twisting deformation of the first deforming portion 28 and the second deforming portion 40 arises, and the limit load by the torsion shaft 24 is made to be a high load.

On the other hand, as shown in FIG. 16, before the first locking mechanism 32 operates, when the vehicle enters into a state of rapid deceleration or a state immediately before rapid deceleration and the gas generator 112 is operated, the piston 110 is pushed-out toward the lateral side of the upper end portion of the cylinder 108 while breaking the positioning portion, and the engagement of the upper end of the piston 110 with the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90 is released. In this state, if rotational force in the pull-out direction is transmitted to the lock ring 90 via the spool 20, the second lock base 46 and the second lock pawls 50, the lock ring 90 rotates in the pull-out direction. Therefore, only energy absorption due to twisting deformation of the first deforming portion 28 arises, and the limit load by the torsion shaft 24 is made to be a low load.

Here, the second locking mechanism 44 is structured such that nothing is interposed between the lock ring 90 and the piston 110 which is driven by the gas generator 112. Therefore, the number of parts of the second locking mechanism 44 can be reduced, and the structure of the second locking mechanism 44 can be made to be simple. In this way, the work of assembling the second locking mechanism 44 can be made to be easy, and costs can be reduced.

Further, the piston 110 is engaged with the outer peripheral groove 96 of the lock ring 90 at one position (the upper end). Therefore, the aligning of the upper end of the piston 110 with respect to the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90 can be made to be simple, the precision of assembling the piston 110 with respect to the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90 can easily be improved, and the piston 110 can appropriately restrict rotation of the lock ring 90 in the pull-out direction.

The piston 110 partially projects-out from the upper end portion of the cylinder 108, and the upper end of the piston 110 is engaged with the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90. Therefore, the shape of the piston 110 for preventing rotation of the lock ring 90 in the pull-out direction can be made to be simple, and the strength of the piston 110 can be made to be high.

Further, after the gas generator 112 is operated, the state, in which the interior of the cylinder 108 is made to be high pressure due to the gas generated by the gas generator 112 and the piston 110 is pushed-out toward the lateral side of the upper end portion of the cylinder 108, is maintained. Therefore, after the gas generator 112 is operated, the piston 110 can reliably be prevented from engaging with the winding direction side surface 96A of the outer peripheral groove 96 of the lock ring 90, and it is possible to reliably prevent rotation of the lock ring 90 in the pull-out direction from being restricted unnecessarily.

Fourth Exemplary Embodiment

A fourth exemplary embodiment of the present invention will be described next by using FIG. 17 through FIG. 20.

A webbing retractor 400 relating to the present exemplary embodiment has a structure which is substantially similar to that of the first exemplary embodiment, but differs with respect to the following points.

As shown in FIG. 17 and FIG. 18, at the webbing retractor 400 relating to the present exemplary embodiment, a stopper portion placement hole 402, which is substantially hemispherical and serves as an engaged portion, is formed at a portion of the outer periphery of the lock ring 90. The lower end of the stopper portion placement hole 402 is open from the outer periphery of the lock ring 90. A stopper portion accommodating hole 404, which is pillar-shaped and communicates with the circular hole 88, is formed at the base 86 so as to correspond to the stopper portion placement hole 402.

The cylinder accommodating hole 106 of the base 86 communicates with the stopper portion accommodating hole 404. The piston 110, which is accommodated at the upper end portion of the cylinder 108 which is fixed to the inner side of the cylinder accommodating hole 106, is structured by a stopper portion 406, which is shaped as a shaft and is at the upper side, and a piston portion 408, which is shaped as a plate and is at the lower side, being formed integrally. The piston 110 functions also as an operating member. The stopper portion 406 projects-out upwardly from the piston portion 408. The stopper portion 406 passes through the top wall of the cylinder 108, and the upper end of the stopper portion 406 is engaged with (inserted in) the stopper portion placement hole 402 of the lock ring 90 via the stopper portion accommodating hole 404. The piston 110 (the piston portion 408) is positioned by a positioning portion (e.g., a positioning projection which is formed at the cylinder 108), and downward movement of the piston 110 within the cylinder 108 is restricted.

In the state in which the upper end of the stopper portion 406 of the piston 110 is engaged with the stopper portion placement hole 402 of the lock ring 90, if the lock ring 90 attempts to rotate in the pull-out direction, the stopper portion 406 receives the rotational force of the lock ring 90 in the pull-out direction, and rotation of the lock ring 90 in the pull-out direction is restricted (prevented).

When the gas generator 112 is operated, the piston 110 (the piston portion 408) is moved downward within the cylinder 108 while breaking the stopper portion 406 (i.e., is driven and operated), and the engagement of the upper end of the piston portion 408 with the stopper portion placement hole 402 of the lock ring 90 is released.

As shown in FIG. 19, in the state in which the vehicle enters a state of rapid deceleration, and the second lock pawls 50 mesh-together with the lock ring 90, and the lock ring 90 attempts to rotate in the pull-out direction via the spool 20, the second lock base 46 and the second lock pawls 50, if the upper end of the stopper portion 406 of the piston 110 is engaged with the stopper portion placement hole 402 of the lock ring 90, rotation of the lock ring 90 in the pull-out direction is restricted by the stopper portion 406. Therefore, energy absorption due to twisting deformation of the first deforming portion 28 and the second deforming portion 40 arises, and the limit load by the torsion shaft 24 is made to be a high load.

On the other hand, as shown in FIG. 20, before the first locking mechanism 32 operates, when the vehicle enters into a state of rapid deceleration or a state immediately before rapid deceleration and the gas generator 112 is operated, the piston 110 (the piston portion 408) is moved downward within the cylinder 108 while breaking the positioning portion, and the engagement of the piston 110 (the upper end of the stopper portion 406) with the stopper portion placement hole 402 of the lock ring 90 is released. In this state, if rotational force in the pull-out direction is transmitted to the lock ring 90 via the spool 20, the second lock base 46 and the second lock pawls 50, the lock ring 90 rotates in the pull-out direction. Therefore, only energy absorption due to twisting deformation of the first deforming portion 28 arises, and the limit load by the torsion shaft 24 is made to be a low load.

Here, the second locking mechanism 44 is structured such that nothing is interposed between the lock ring 90 and the piston 110 which is driven by the gas generator 112. Therefore, the number of parts of the second locking mechanism 44 can be reduced, and the structure of the second locking mechanism 44 can be made to be simple. In this way, the work of assembling the second locking mechanism 44 can be made to be easy, and costs can be reduced.

Further, the stopper portion 406 of the piston 110 is engaged with the stopper portion placement hole 402 of the lock ring 90 at one position (the upper end). Therefore, the aligning of the piston 110 (the stopper portion 406) with respect to the stopper portion placement hole 402 of the lock ring 90 can be made to be simple, the precision of assembling the piston 110 (the stopper portion 406) with respect to the stopper portion placement hole 402 of the lock ring 90 can easily be improved, and the stopper portion 406 of the piston 110 can appropriately restrict rotation of the lock ring 90 in the pull-out direction.

The upper end of the stopper portion 406 of the piston 110 is engaged with the stopper portion placement hole 402 of the lock ring 90. Therefore, the shape of the piston 110 (the stopper portion 406) for preventing rotation of the lock ring 90 in the pull-out direction can be made to be simple, and the strength of the piston 110 (the stopper portion 406) can be made to be high.

Further, after the gas generator 112 is operated, the state, in which the interior of the cylinder 108 is made to be high pressure due to the gas generated by the gas generator 112 and the piston 110 (the piston portion 408) is moved downward within the cylinder 108, is maintained. Therefore, after the gas generator 112 is operated, the upper end of the stopper portion 406 of the piston 110 can reliably be prevented from engaging with the stopper portion placement hole 402 of the lock ring 90, and it is possible to reliably prevent rotation of the lock ring 90 in the pull-out direction from being restricted unnecessarily.

Fifth Exemplary Embodiment

A fifth exemplary embodiment of the present invention will be described next by using FIG. 21 through FIG. 24.

A webbing retractor 500 relating to the present exemplary embodiment has a structure which is substantially similar to that of the first exemplary embodiment, but differs with respect to the following points.

As shown in FIG. 21 and FIG. 22, at the webbing retractor 500 relating to the present exemplary embodiment, a stopper accommodating hole 502 which communicates with the circular hole 88 is formed in the base 86 so as to correspond to the outer peripheral groove 96 of the outer periphery of the lock ring 90. A stopper 504, which is substantially shaped as a rectangular plate and serves as an operating member, is accommodated within the stopper accommodating hole 502. A piston accommodating hole 506 is formed in the base 86, and communicates with the lower end of the stopper accommodating hole 502.

The cylinder accommodating hole 106 of the base 86 communicates with the piston accommodating hole 506. The piston 110, which is shaped as an L-shaped plate and is partially accommodated at the upper end portion of the cylinder 108 which is fixed to the inner side of the cylinder accommodating hole 106, projects-out into the stopper accommodating hole 502 and is disposed beneath the stopper 504. In this way, downward movement of the stopper 504 is prevented by the piston 110, and the upper end of the stopper 504 is engaged with (inserted in) the outer peripheral groove 96 of the lock ring 90.

In the state in which the upper end of the stopper 504 is engaged with the outer peripheral groove 96 of the lock ring 90, if the lock ring 90 attempts to rotate in the pull-out direction, the stopper 504 receives the rotational force of the lock ring 90 in the pull-out direction, and rotation of the lock ring 90 in the pull-out direction is restricted (prevented).

When the gas generator 112 is operated and the piston 110 is pushed-out sideways from the upper end portion of the cylinder 108, the prevention of the downward movement of the stopper 504 by the piston 110 is released, and the stopper 504 is moved (dropped) downward (is operated).

As shown in FIG. 23, in the state in which the vehicle enters a state of rapid deceleration, and the second lock pawls 50 mesh-together with the lock ring 90, and the lock ring 90 attempts to rotate in the pull-out direction via the spool 20, the second lock base 46 and the second lock pawls 50, if the upper end of the stopper 504 is engaged with the outer peripheral groove 96 of the lock ring 90, rotation of the lock ring 90 in the pull-out direction is restricted by the stopper 504. Therefore, energy absorption due to twisting deformation of the first deforming portion 28 and the second deforming portion 40 arises, and the limit load by the torsion shaft 24 is made to be a high load.

On the other hand, as shown in FIG. 24, before the first locking mechanism 32 operates, when the vehicle enters into a state of rapid deceleration or a state immediately before rapid deceleration and the gas generator 112 is operated, due to the piston 110 being pushed-out sideways from the upper end portion of the cylinder 108, the prevention of the downward movement of the stopper 504 by the piston 110 is released, and the stopper 504 is moved downward, and the engagement of the upper end of the stopper 504 with the outer peripheral groove 96 of the lock ring 90 is released. In this state, if rotational force in the pull-out direction is transmitted to the lock ring 90 via the spool 20, the second lock base 46 and the second lock pawls 50, the lock ring 90 rotates in the pull-out direction. Therefore, only energy absorption due to twisting deformation of the first deforming portion 28 arises, and the limit load by the torsion shaft 24 is made to be a low load.

Here, the second locking mechanism 44 is structured such that only the stopper 504 is interposed between the lock ring 90 and the piston 110 which is driven by the gas generator 112. Therefore, the number of parts of the second locking mechanism 44 can be reduced, and the structure of the second locking mechanism 44 can be made to be simple. In this way, the work of assembling the second locking mechanism 44 can be made to be easy, and costs can be reduced.

Further, the stopper 504 is engaged with the outer peripheral groove 96 of the lock ring 90 at one position (the upper end). Therefore, the aligning of the stopper 504 with respect to the outer peripheral groove 96 of the lock ring 90 can be made to be simple, the precision of assembling the stopper 504 with respect to the outer peripheral groove 96 of the lock ring 90 can easily be improved, and the stopper 504 can appropriately restrict rotation of the lock ring 90 in the pull-out direction.

The upper end of the stopper 504 is engaged with the outer peripheral groove 96 of the lock ring 90. Therefore, the shape of the upper end of the stopper 504 for preventing rotation of the lock ring 90 in the pull-out direction can be made to be simple, and the strength of the stopper 504 can be made to be high.

Sixth Exemplary Embodiment

A sixth exemplary embodiment of the present invention will be described next by using FIG. 25 through FIG. 28.

A webbing retractor 600 relating to the present exemplary embodiment has a structure which is substantially similar to that of the first exemplary embodiment, but differs with respect to the following points.

As shown in FIG. 25 and FIG. 26, at the webbing retractor 600 relating to the present exemplary embodiment, a stopper shaft accommodating hole 602 which communicates with the circular hole 88 is formed in the base 86 so as to correspond to the outer peripheral groove 96 of the outer periphery of the lock ring 90, and a stopper main body accommodating hole 604, which communicates with the lower end of the stopper shaft accommodating hole 602, is formed. A stopper 606 serving as an operating member is accommodated within the stopper shaft accommodating hole 602 and the stopper main body accommodating hole 604. The stopper 606 is structured by the lower end of a shaft-shaped stopper shaft 608 being fixed to the upper end of a rectangular-plate-shaped stopper main body 610. The stopper shaft 608 and the stopper main body 610 are accommodated in the stopper shaft accommodating hole 602 and the stopper main body accommodating hole 604, respectively. The upper end of the stopper shaft 608 is thereby engaged with (inserted in) the outer peripheral groove 96 of the lock ring 90.

In the state in which the upper end of the stopper shaft 608 is engaged with the outer peripheral groove 96 of the lock ring 90, if the lock ring 90 attempts to rotate in the pull-out direction, the stopper 606 receives the rotational force of the lock ring 90 in the pull-out direction, and rotation of the lock ring 90 in the pull-out direction is restricted (prevented).

The cylinder accommodating hole 106 of the base 86 communicates with the side portion of the stopper main body accommodating hole 604. The piston 110, which is accommodated in one end of the cylinder 108 which is fixed to the inner side of the cylinder accommodating hole 106, is disposed at the lateral side of the stopper main body 610.

When the gas generator 112 is operated and the piston 110 is pushed-out sideways from one end of the cylinder 108, the stopper main body 610 is moved sideways by the piston 110, the stopper shaft 608 and the stopper main body 610 are separated, and the stopper shaft 608 is moved (dropped) downward (the stopper 606 is operated).

As shown in FIG. 27, in the state in which the vehicle enters a state of rapid deceleration, and the second lock pawls 50 mesh-together with the lock ring 90, and the lock ring 90 attempts to rotate in the pull-out direction via the spool 20, the second lock base 46 and the second lock pawls 50, if the upper end of the stopper shaft 608 is engaged with the outer peripheral groove 96 of the lock ring 90, rotation of the lock ring 90 in the pull-out direction is restricted by the stopper 606. Therefore, energy absorption due to twisting deformation of the first deforming portion 28 and the second deforming portion 40 arises, and the limit load by the torsion shaft 24 is made to be a high load.

On the other hand, as shown in FIG. 28, before the first locking mechanism 32 operates, when the vehicle enters into a state of rapid deceleration or a state immediately before rapid deceleration and the gas generator 112 is operated, due to the piston 110 being pushed-out sideways from one end of the cylinder 108, the stopper main body 610 is moved sideways by the piston 110, the stopper shaft 608 and the stopper main body 610 are separated, the stopper shaft 608 is moved downward, and the engagement of the upper end of the stopper shaft 608 with the outer peripheral groove 96 of the lock ring 90 is released. In this state, if rotational force in the pull-out direction is transmitted to the lock ring 90 via the spool 20, the second lock base 46 and the second lock pawls 50, the lock ring 90 rotates in the pull-out direction. Therefore, only energy absorption due to twisting deformation of the first deforming portion 28 arises, and the limit load by the torsion shaft 24 is made to be a low load.

Here, the second locking mechanism 44 is structured such that only the stopper 606 is interposed between the lock ring 90 and the piston 110 which is driven by the gas generator 112. Therefore, the number of parts of the second locking mechanism 44 can be reduced, and the structure of the second locking mechanism 44 can be made to be simple. In this way, the work of assembling the second locking mechanism 44 can be made to be easy, and costs can be reduced.

Further, the stopper shaft 608 of the stopper 606 is engaged with the outer peripheral groove 96 of the lock ring 90 at one position (the upper end). Therefore, the aligning of the stopper 606 (the stopper shaft 608) with respect to the outer peripheral groove 96 of the lock ring 90 can be made to be simple, the precision of assembling the stopper 606 (the stopper shaft 608) with respect to the outer peripheral groove 96 of the lock ring 90 can easily be improved, and the stopper 606 can appropriately restrict rotation of the lock ring 90 in the pull-out direction.

The upper end of the stopper shaft 608 is engaged with the outer peripheral groove 96 of the lock ring 90. Therefore, the shape of the stopper 606 (the upper end of the stopper shaft 608) for preventing rotation of the lock ring 90 in the pull-out direction can be made to be simple, and the strength of the stopper 606 (the upper end of the stopper shaft 608) can be made to be high. 

1. A webbing retractor comprising: a winding shaft on which a webbing, which can be applied to a vehicle occupant, is wound, the webbing being pulled out by the winding shaft being rotated in a pull-out direction; a force limiter mechanism which, at a time of an emergency situation with respect to a vehicle, permits rotation of the winding shaft in the pull-out direction and limits a load, which is applied to the vehicle occupant from the webbing, to a limit load; and a switching portion having a driving member which is configured to be driven at a time of an emergency situation with respect to the vehicle, an operating member directly operated by driving of the driving member, and a moving member which is engaged with the operating member and movement of which is permitted by operation of the operating member, the switching portion switching the limit load from a high load to a low load in response to the movement of the moving member being permitted.
 2. The webbing retractor of claim 1, wherein the winding shaft is hollow along the central axis thereof, the force limiter mechanism is accommodated within the winding shaft, and a first locking portion and the switching portion, which serves as a second locking portion, are coaxially connected at either end side of the winding shaft.
 3. The webbing retractor of claim 1, wherein the force limiter mechanism, serving as a first energy absorbing member, includes a first deforming portion which is connected between a portion which is joined to the winding shaft and the first locking portion and a second deforming portion which is connected between the portion which is joined to the winding shaft and the second locking portion (the switching portion), and is twistable by a rotational force in the pull-out direction of the winding shaft.
 4. The webbing retractor of claim 1, wherein a stopper accommodating hole for accommodating a stopper wire serving as a second energy absorbing member is formed in the winding shaft, one end portion of the stopper wire is disposed within a wire guiding portion which is formed at least either one of a first locking portion side end portion of the winding shaft and a winding shaft side end portion of the first locking portion, and the other end of the stopper wire is disposed within an accommodating hole formed in the second locking portion.
 5. The webbing retractor of claim 1, wherein only the operating member is interposed between the moving member and the driving member.
 6. The webbing retractor of claim 1, wherein the operating member is engaged with the moving member at one position.
 7. The webbing retractor of claim 1, wherein a supporting position of the operating member is disposed at a pull-out direction side of the moving member, with respect to an engaging position of the operating member with the moving member.
 8. A webbing retractor comprising: a winding shaft on which a webbing, which can be worn by a vehicle occupant, is wound, the webbing being pulled out by the winding shaft being rotated in a pull-out direction; a force limiter mechanism which, at a time of an emergency situation with respect to a vehicle, permits rotation of the winding shaft in the pull-out direction and limits a load, which is applied to the vehicle occupant from the webbing, to a limit load; and a switching portion having a driving member which is configured to be driven at a time of an emergency situation with respect to the vehicle, and a moving member which is engaged with the driving member and movement of which is permitted by driving of the driving member, the switching portion switching the limit load from a high load to a low load in response to the movement of the moving member being permitted.
 9. The webbing retractor of claim 8, wherein the winding shaft is hollow along the central axis thereof, the force limiter mechanism is accommodated within the winding shaft, and a first locking portion and the switching portion which serves as a second locking portion are coaxially connected at either end side of the winding shaft.
 10. The webbing retractor of claim 8, wherein the force limiter mechanism, serving as a first energy absorbing member, includes a first deforming portion which is connected between a portion which is joined to the winding shaft and the first locking portion and a second deforming portion which is connected between the portion which is joined to the winding shaft and the second locking portion (the switching portion), and is twistable by a rotational force in the pull-out direction of the winding shaft.
 11. The webbing retractor of claim 8, wherein a stopper accommodating hole for accommodating a stopper wire serving as a second energy absorbing member is formed in the winding shaft, one end portion of the stopper wire is disposed within a wire guiding portion which is formed at least either one of a first locking portion side end portion of the winding shaft and a winding shaft side end portion of the first locking portion, and the other end of the stopper wire is disposed within an accommodating hole formed in the second locking portion.
 12. The webbing retractor of claim 8, wherein nothing is interposed between the driving member and the moving member.
 13. The webbing retractor of claim 8, wherein the driving member is engaged with the moving member at one position.
 14. A webbing retractor comprising: a winding shaft on which a webbing, which can be worn by a vehicle occupant, is wound, the webbing being pulled out by the winding shaft being rotated in a pull-out direction; a force limiter mechanism which, at a time of an emergency situation with respect to a vehicle, permits rotation of the winding shaft in the pull-out direction and limits a load, which is applied to the vehicle occupant from the webbing, to a limit load; and a switching portion having an operating member which is configured to be operated at a time of an emergency situation with respect to the vehicle, and a moving member which is engaged with the operating member at one position with prevention and permission of movement thereof being alternated between by operation of the operating member, the switching portion switching the limit load between a high load and a low load in response to alternation between the operation and non-operation of the operating member.
 15. The webbing retractor of claim 14, wherein the winding shaft is hollow along the central axis thereof, the force limiter mechanism is accommodated within the winding shaft, and a first locking portion and the switching portion which serves as a second locking portion are coaxially connected at either end side of the winding shaft.
 16. The webbing retractor of claim 14, wherein the force limiter mechanism, serving as a first energy absorbing member, includes a first deforming portion which is connected between a portion which is joined to the winding shaft and the first locking portion and a second deforming portion which is connected between the portion which is joined to the winding shaft and the second locking portion (the switching portion), and is twistable by a rotational force in the pull-out direction of the winding shaft.
 17. The webbing retractor of claim 14, wherein a stopper accommodating hole for accommodating a stopper wire serving as a second energy absorbing member is formed in the winding shaft, one end portion of the stopper wire is disposed within a wire guiding portion which is formed at least either one of a first locking portion side end portion of the winding shaft and a winding shaft side end portion of the first locking portion, and the other end of the stopper wire is disposed within an accommodating hole formed in the second locking portion.
 18. A webbing retractor comprising: a winding shaft on which a webbing, which can be worn by a vehicle occupant, is wound, the webbing being pulled out by the winding shaft being rotated in a pull-out direction; a force limiter mechanism which, at a time of an emergency situation with respect to a vehicle, permits rotation of the winding shaft in the pull-out direction and limits a load, which is applied to the vehicle occupant from the webbing, to a limit load; and a switching portion having an operating member which is configured to be operated at a time of an emergency situation with respect to the vehicle, and a moving member which is engaged with the operating member with prevention and permission of movement thereof being alternated between by operation of the operating member, a supporting position of the operating member being disposed at a moving direction side with respect to an engaging position of the operating member, and the switching portion switching the limit load between a high load and a low load in response to alternation between the operation and non-operation of the operating member.
 19. The webbing retractor of claim 18, wherein the winding shaft is hollow along the central axis thereof, the force limiter mechanism is accommodated within the winding shaft, and a first locking portion and the switching portion which serves as a second locking portion are coaxially connected at either end side of the winding shaft.
 20. The webbing retractor of claim 18, wherein the force limiter mechanism, serving as a first energy absorbing member, includes a first deforming portion which is connected between a portion which is joined to the winding shaft and the first locking portion and a second deforming portion which is connected between the portion which is joined to the winding shaft and the second locking portion (the switching portion), and is twistable by a rotational force in the pull-out direction of the winding shaft.
 21. The webbing retractor of claim 18, wherein a stopper accommodating hole for accommodating a stopper wire serving as a second energy absorbing member is formed in the winding shaft, one end portion of the stopper wire is disposed within a wire guiding portion which is formed at least either one of a first locking portion side end portion of the winding shaft and a winding shaft side end portion of the first locking portion, and the other end of the stopper wire is disposed within an accommodating hole formed in the second locking portion.
 22. The webbing retractor of claim 18, wherein the operating member is engaged with the moving member at one position.
 23. A webbing retractor comprising: a winding shaft on which a webbing, which can be worn by a vehicle occupant, is wound, the webbing being pulled out by the winding shaft being rotated in a pull-out direction; a force limiter mechanism which, at a time of an emergency situation with respect to a vehicle, permits rotation of the winding shaft in the pull-out direction and limits a load, which is applied to the vehicle occupant from the webbing, to a limit load; and a switching portion having an operating member which is configured to be operated via pressure of a fluid at a time of an emergency situation with respect to the vehicle and with an operated state thereof being maintained via the pressure of the fluid, and a moving member, prevention and permission of movement thereof being alternated between by operation of the operating member, the switching portion switching the limit load between a high load and a low load in response to alternation between the operation and non-operation of the operating member.
 24. The webbing retractor of claim 23, wherein the winding shaft is hollow along the central axis thereof, the force limiter mechanism is accommodated within the winding shaft, and a first locking portion and the switching portion which serves as a second locking portion are coaxially connected at either end side of the winding shaft.
 25. The webbing retractor of claim 23, wherein the force limiter mechanism, serving as a first energy absorbing member, includes a first deforming portion which is connected between a portion which is joined to the winding shaft and the first locking portion and a second deforming portion which is connected between the portion which is joined to the winding shaft and the second locking portion (the switching portion), and is twistable by a rotational force in the pull-out direction of the winding shaft.
 26. The webbing retractor of claim 23, wherein a stopper accommodating hole for accommodating a stopper wire serving as a second energy absorbing member is formed in the winding shaft, one end portion of the stopper wire is disposed within a wire guiding portion which is formed at least either one of a first locking portion side end portion of the winding shaft and a winding shaft side end portion of the first locking portion, and the other end of the stopper wire is disposed within an accommodating hole formed in the second locking portion.
 27. The webbing retractor of claim 23, wherein the operating member is engaged with the moving member at one position. 